linux-kernel - Re: [PATCH] Bluetooth: Apply initial command workaround for more Intel chips

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Date:   Sun, 5 Dec 2021 11:33:04 +0100
From:   Fernando Ramos <greenfoo@....eu>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Paul Menzel <pmenzel@...gen.mpg.de>,
        Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Tedd Ho-Jeong An <tedd.an@...el.com>,
        linux-kernel@...r.kernel.org, linux-bluetooth@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: Apply initial command workaround for more
 Intel chips

On 21/12/02 05:47PM, Takashi Iwai wrote:
> Thanks, so this seems depending on the hardware, maybe a subtle
> difference matters.  As far as I read the code changes, the workaround
> was applied in the past unconditionally, so it must be fairly safe
> even if the chip works as is.
> 
> Or, for avoiding the unnecessarily application of the workaround,
> should it be changed as a fallback after the failure at the first
> try...?

I don't know if this helps, but I started experiencing this same issue ("hci0:
command 0xfc05 tx timeout") yesterday after a kernel upgrade.

My controller is a different one:

    8087:0025 Intel Corp. Wireless-AC 9260 Bluetooth Adapter
    ^^^^^^^^^

I tried with different (older) versions of the v5.15.x kernel but none worked.

Now, this is the interesting (?) part: today, when I switched on the computer
to keep testing, the bluetooth was *already* working once again.

I have reviewed my bash history to try to figure out what is it that I did, and
the only thing I see is that yesterday, before going to sleep, I did a full
poweroff instead of a reset (which is what I used yesterday to try different
kernels).

This does not make any sense... but then I found this [1] post from someone else
who experienced the same.

Is there any reasonable explanation for this? Could this be the reason why you
seem to have different results with the same controller (8087:0a2a)?

[1] https://bbs.archlinux.org/viewtopic.php?pid=2006188#p2006188